The new Hydrangea cultivar was found and selected as an isolated specimen in a garden setting in Bishop, Ga., during May of 2015. The seed and pollen parents are unknown.
Asexual reproduction of the new cultivar ‘COF-HM1’ by vegetative soft wood cuttings was first performed during July of 2015, at a commercial greenhouse in Watkinsville, Ga. Subsequent propagation has shown that the unique features of this cultivar are stable and reproduced true to type in 5 successive generations.